As someone who has acquired greater light and truth, you are capable of seeing others and their place in reality to a more accurate extent than they can see themselves. Because you have a broader and deeper view of reality, you can guide them around obstacles they do not see to better outcomes than they are aware. You can emit light by helping them see what is currently darkness to them.
Even when a person is fully reconciled to the light they have, their perception of reality is incorrect or incomplete in every way. While your perspective is likewise incorrect and incomplete, if it is advanced compared to theirs, through your skillful interactions, you can share with them what you’ve obtained while sparing them a great deal of the cost you had to pay to obtain it.
This process of emitting light is akin to what happens with a lighthouse in the dark. A lighthouse shines its light for a moment on each section of the sea as it broadcasts its beam in a circular track. Everything in its spotlight momentarily transforms into what it could be if it were continuously surrounded by light. Shapeless blobs transform into differentiated surfaces, some shining back, others absorbing the light. Then, the beam continues on. Any ship that happened to be touched by the light can decide how to respond to that light.
Because the light inside you is bright, you can use it by allowing it to shine into your observations and reflect back a vision of what could be if they had the same light within them. Then you can share that with them. You can lift the downtrodden by helping them see how much God loves them. You can remove the scales from the blind by helping them see causes and consequences of which they were previously unaware. You can articulate their potential, and help them believe that something better is both possible and attainable.
Your light will bring forth potentialities in others that otherwise would not manifest. The light within you is like salt, which preserves and enhances what it is added to:
13 Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.
14 Ye are the light of the world. A city that is set on an hill cannot be hid.
15 Neither do men light a candle, and put it under a bushel, but on a candlestick; and it giveth light unto all that are in the house.
16 Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven. (Matthew 5)
You have immense capacity for good. Use it.
Be aware that when you shine your light, it will be the minority of people that respond beneficially to it:
27 And the love of men shall wax cold, and iniquity shall abound. 28 And when the times of the Gentiles is come in, a light shall break forth among them that sit in darkness, and it shall be the fulness of my gospel;
29 But they receive it not; for they perceive not the light, and they turn their hearts from me because of the precepts of men. (D&C 45)
The greatest sorrow is to see the potential of what others could be if they embraced the light. It is also the loneliest sorrow, because they don't see it themselves. You bear the weight of knowing what could have been, and you carry that weight alone.
Sorrow is not the only cost you incur by shining your light. Realize that a candle on a hill is a beacon, but it is also a target. As you shine your light, you will find that while some benefit from and respond well to it, it will mostly attract negative attention. Do it anyway.